Instead of posting this multiple times (which we prefer not be done), you will get better assistance if you tell us more, such as your email provider and your account settings and whether you are using any addons and info on your antivirus, if any, plus your OS. Thank you. We may not have an answer, but this would at least increase the odds that someone here may have a suggestion.

Hi David,

     My apologies for the multiple postings--I can see that that is a problem--I just do not know what I am doing.

    I thought my provider was "juno.com".

   I do not know what "account settings" you want to know about or how to find out what they are.  Sorry.

   I do not know what you mean by "add-ons".  I use "NoScript",  "Textmarker", and "Capital One Shopping" with Firefox.  I have Norton 360 installed. My OS is Windows 10.

My apologies, thank you for your help,

Ned Kennington

Okay, I am not familiar with details of many email providers, but I noticed that Juno has a free version and that has a limit of 2 gig for storage. If you're using the free version, that may account for occasionally losing messages. If that applies to you, I encourage you to check your usage. Let us know.

Apparently, after it removes my sent messages from the system's "Sent" folder, the system has been saving all of my sent messages to the ”Archives Folder” in (the name of my account) (on the Thunderbird hardware) in “Yearly archived folders”, because , I have been using the “Archive Messages” option under “Copies and Folders” option under (the name of my account) to “Keep message archives” in the ”Archives Folder” in (the name of my account)(on the Thunderbird hardware) with the “Archive options” button set to store the messages in “Yearly archived folders”. I am planning to have the system start saving these sent messages in Local Folders on my local computer to avoid filling up my space on the Thundebird hardware.